On board an aircraft there are various areas where the exceeding of a predetermined temperature and the development of heat accumulation has to be reliably prevented. Particularly in aircraft areas that are used as installation space for thermally loaded equipment, such as for example the air conditioning units or the electronic control components of the aircraft, an adequate removal of heat from the thermally loaded equipment has to be guaranteed by proper ventilation of these areas both during ground operation and cruising of the aircraft. Furthermore, in aircraft areas used for example as installation space for thermally loaded equipment an adequate exchange of air has to be ensured in order to prevent heating of the aircraft structure and/or the development of accumulations of ignitable fuel and/or fuel vapor.
DE 103 61 657 A1 describes a system for supplying an aircraft area with cooling air, which comprises a ram-air duct with an air inlet as well as a diffuser and a bypass duct extending parallel to a sub-section of the ram-air duct. The ram-air duct runs into a cooling-air plenum chamber, branching off from which are a supply line of an unpressurized bay ventilation (UBV) system, a supply line of an oxygen generating system and a supply line of an inert-gas generating system. Through the supply line of the UBV system ventilation air is supplied to an aircraft area that is to be ventilated. In the supply lines of the oxygen generating system and the inert-gas generating system, on the other hand, in each case a heat exchanger is arranged, which is supplied with cooling energy by the air flowing through the ram-air duct.
During cruising of the aircraft, in the ram-air duct there is a build-up, relative to the ambient pressure, of a static overpressure that is also referred to as ram pressure, which effects a flow of ambient air through the ram-air duct, the cooling-air plenum chamber and the supply lines connected to the cooling-air plenum chamber. During ground operation of the aircraft, on the other hand, an air compressor arranged in the bypass duct ensures an adequate flow of air through the ram-air duct, the cooling-air plenum chamber and the supply lines connected to the cooling-air plenum chamber.
The cooling air supply system known from DE 103 61 657 A1 performs the dual function of, on the one hand, supplying ventilation air to an aircraft area to be ventilated and, on the other hand, ensuring a proper supply of cooling energy to the heat exchangers of the oxygen generating system and the inert-gas generating system. The integration of the heat exchangers of the oxygen generating system and the inert-gas generating system into the cooling air supply system supplying ventilation air to an aircraft area to be ventilated therefore makes it possible to dispense with a separate ram-air duct for supply of the heat exchangers with cooling energy. As a result, weight- and cost savings can be realized, the installation space requirement of the overall system can be reduced and consequently the fuel consumption of the aircraft while cruising can be decreased.
A drawback of the cooling air supply system described in DE 103 61 657 A1 is however that, because of the system layout comprising a cooling-air plenum chamber and three supply lines connected parallel to one another to the cooling-air plenum chamber, in all operating states of the system, i.e. both when the aircraft is situated on the ground and during cruising of the aircraft, a proper supply of the UBV system with ventilation air requires taking into account the pressure drop caused by the heat exchangers of the oxygen generating system and the inert-gas generating system. Consequently, the air compressor arranged in the bypass duct and the air inlet of the ram-air duct have to be dimensioned in a way that allows an adequate quantity of ventilation air to be supplied to the UBV system also during ground operation of the aircraft despite the pressure drop caused by the heat exchangers of the oxygen generating system and the inert-gas generating system.
The underlying object of the present invention is to provide a system for ventilation of an aircraft area, which both during ground operation and during cruising of an aircraft guarantees a reliable ventilation of an aircraft area to be supplied with ventilation air and additionally during cruising of the aircraft enables a proper and energy-efficient supply of cooling energy to a heat exchanger integrated into the ventilation system.